The present invention relates to an electrically actuatable fuel-injection valve.
An electrically actuatable fuel-injection valve for internal combustion engines has a piezoelectric oscillator which is provided with electrodes, and has at least one fuelreceiving chamber which is in communication with a fuel feed path and with an ejection opening (outlet opening), the valve having a block in which the oscillator is mounted and out of which, in particular, the fuel feed path is formed.
This device is an electrically actuatable fuel-injection valve for internal combustion engines which is characterized by the fact that it has a piezoelectric oscillator which is provided with electrodes and has at least one fuel-receiving chamber, that a fuel feed path and an ejection opening (outlet opening) are in fuel-conducting communication with the chamber and are so shaped that, upon the application of a voltage to the electrodes, the fuel is imparted a preferred movement through the chamber to the ejection opening. In particular, the piezoelectric oscillator is mounted in a block out of which the fuel feed path is formed. The piezoelectric oscillator is preferably developed as a hollow cylindrical radial oscillator in whose wall a number of fuelreceiving chambers are arranged parallel and concentric to its longitudinal axis. One end of the radial oscillator with the continuous chambers extends preferably into an annular constant-volume chamber which is formed out of the block concentrically to the longitudinal axis.
The fuel-injection valve operates in accordance with the principle that, after the application of an electric voltage to the electrodes of the piezoelectric oscillator, and the corresponding formation of an electric field between the electrodes of the oscillator and corresponding change in thickness, the oscillator, without any element which is movable as a whole and in particular without a displaceable valve needle, determines the preferred direction of movement in which the fuel is injected into the surrounds of the fuel-injection valve. In this connection, the fuel-injection valve measures the required injection amount and creates the requisite condition for the atomizing of the fuel. This is achieved in the manner that, due to the electric field, upon the application of the high voltage to the electrodes of the piezoelectric oscillator, the latter contracts or expands so that the volume of the fuel-receiving chamber changes and that, upon a reduction in volume of the chamber, the fuel emerges essentially from the ejection opening while the return flow of fuel through the fuel feed path is substantially throttled.
For the operation of the piezoelectric oscillator a high voltage is necessary which is to be fed to the electrodes of the oscillator. This controlled high voltage can cause interference in other electrical systems including, in particular, radio systems which are located in the vicinity of the high voltage generator and the high-voltage lines to the fuel-injection valve with the oscillator.